stihl 066 magnum manual

The STIHL 066 Magnum is a professional-grade chainsaw featuring a high-performance engine, advanced anti-vibration system, electronic ignition, automatic oiling, and a decompression valve for easier starting. Designed for demanding forestry and felling work, it requires proper handling, maintenance, and safety procedures. Below are key sections for safety, features, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Safety Information 3. Assembly & Preparation 4. Specifications 5. Controls and Components 6. Starting & Operation 7. Maintenance Schedule 8. Chain & Bar Care 9. Fuel & Lubrication 10. Storage Guidelines 11. Troubleshooting

Features at a Glance

Key components: High-torque engine, anti-vibration handles, QuickStop chain brake, side-access chain tensioner, decompression valve, and STIHL ElastoStart starter grip.

Feature	Description
Engine Displacement	91.1 cc (5.56 cu. in.)
Power Output	High-performance professional grade
Anti-Vibration System	Reduces operator fatigue during extended use
Ignition System	Electronic ignition (CDI) for reliable starting
Decompression Valve	Reduces compression for easier pull-starting
Chain Brake	QuickStop inertia-activated safety feature
Oiling System	Automatic and manual chain oiling
Fuel Tank Capacity	Approx. 825 ml (28 fl. oz.)
Oil Tank Capacity	Approx. 360 ml (12.2 fl. oz.)
Recommended Bar Length	20" to 36" (50 cm to 90 cm)

Safety Information

Always wear protective equipment: helmet, eye protection, hearing protection, gloves, chainsaw chaps, and sturdy boots.

Clear work area of obstacles and bystanders.
Inspect saw before each use: chain sharpness, tension, and lubrication.
Never operate with damaged or missing safety devices.
Use proper fueling procedures away from ignition sources.
Always engage chain brake when carrying or not cutting.

WARNING! Kickback can occur without warning. Hold saw firmly with both hands, avoid tip contact, and maintain a secure stance.

Assembly & Preparation

Unpack and inspect all parts. Assemble guide bar and chain.

Attach guide bar: Loosen nuts, position bar on studs, align chain drive links with sprocket.
Install chain: Place chain over bar with cutters facing forward on top.
Tension chain: Adjust with side-access tensioner until chain snaps back when pulled from bar.
Fill tanks: Add STIHL HP Ultra oil to fuel mix (50:1 ratio) and bar/chain oil to oil tank.
Check controls: Ensure throttle trigger, throttle lockout, and chain brake function properly.

CAUTION! Use only STIHL-approved bars, chains, and lubricants. Incorrect assembly can cause injury.

Specifications

Engine Type: 2-stroke, single cylinder, air-cooled.
Displacement: 91.1 cc (5.56 cu. in.).
Powerhead Weight: Approx. 7.5 kg (16.5 lbs) without bar and chain.
Fuel/Oil Ratio: 50:1 with STIHL HP Ultra oil.
Ignition: Electronic, CDI.
Chain Pitch/Gauge: .404" or 3/8" pitch; .063" gauge typical.
Sound Power Level: Meets applicable noise regulations.
Vibration Levels: Front/Rear handle: below industry thresholds.
Warranty: Limited warranty for professional use.

Controls and Components

Main controls: Front handle with chain brake, rear handle with throttle trigger, throttle lockout, master control lever (choke/start/run), decompression valve, and stop switch.

Master Control Lever: Positions: STOP (0), START (choke), RUN. Chain Brake: Activate manually (push forward) or by inertia. Decompression Valve: Button to press before starting cold engine. Throttle Lockout: Must be depressed to engage throttle. Side Tensioner: For chain adjustment without tools.

Starting & Operation

Starting procedure (cold engine):

Engage chain brake. Place on firm ground.
Press decompression valve (if equipped).
Set master control to START (choke).
Pull starter handle until engine fires (1-2 pulls).
Move master control to RUN. Pull again to start.
Blip throttle to disengage fast idle.

Operation Tips: Use full throttle when cutting. Let chain do the work; avoid forcing. Maintain proper chain lubrication.

Maintenance Schedule

Daily: Clean air filter, check chain tension and sharpness, inspect bar for wear. Weekly: Clean cooling fins, check spark plug, clean fuel filter. Monthly: Check all nuts and bolts, inspect anti-vibration elements, clean spark arrestor screen.

Air Filter: Clean with compressed air or soapy water; replace if damaged. Spark Plug: Gap 0.5 mm (0.020"); replace annually. Fuel Filter: Replace every 3 months or as needed.

Chain & Bar Care

Sharpen chain regularly with round file and guide. Maintain correct depth gauge settings. Rotate bar periodically to ensure even wear. Clean bar groove and oil holes.

Chain Tension: Correct when snug against bar but can be pulled around by hand. Re-tension when chain sags. Bar Maintenance: File down burrs, dress rails with flat file.

Fuel & Lubrication

Use fresh 89 octane gasoline mixed with STIHL HP Ultra oil at 50:1 ratio. Do not use fuel older than 30 days. Use STIHL bar and chain oil or equivalent for lubrication. Check oil flow by pointing at light surface; adjust oiler if needed.

WARNING! Fuel is highly flammable. No smoking. Refuel in well-ventilated area with engine off and cool.

Storage Guidelines

For long-term storage: Empty fuel tank and run engine dry. Remove chain, clean and oil it. Clean entire saw. Store in dry, cool place. For short-term: Add fuel stabilizer to tank.

CAUTION! Storing with fuel can cause carburetor damage and starting problems.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, flooded, fuel issue	Check spark plug, use correct starting procedure, ensure fresh fuel mix.
Engine runs poorly	Dirty air filter, clogged fuel filter	Clean/replace air filter, replace fuel filter.
Chain doesn't oil	Empty oil tank, clogged oil holes	Fill tank, clean bar oil passages, check oil pump.
Excessive vibration	Loose components, worn AV mounts	Tighten all bolts, inspect anti-vibration elements.
Chain dulls quickly	Hitting ground, improper filing	Avoid contact with dirt, sharpen correctly with proper file size.

Service: For major repairs, contact authorized STIHL servicing dealer.

Support: Refer to official STIHL website or contact customer service.